Three-dimensional printing method

ABSTRACT

A predetermined area of a print surface is captured by a camera as a plurality of subdivided images to include an end edge portion of a previously printed image on a coating-target object, the end edge portion serving as a connection portion with an image to be drawn to be printed contiguous to the printed image, a composite print surface, which is a plane projection of the print-target surface which is non-plane, is created on the basis of the captured subdivided images, an edited image to be drawn is created by superimposing the image to be drawn on the composite print surface, and the image to be drawn is adjacently printed contiguous to the printed image on the basis of the edited image to be drawn.

BACKGROUND Technical Field

The present invention relates to a three-dimensional printing method,and more specifically to a three-dimensional printing method capable ofcontinuously printing end edges of adjacent images in a case ofadjacently printing a plurality of images on a surface of an objecthaving a three-dimensional shape by an inkjet printer.

Related Art

A drawing method using an inkjet method has been proposed for coatingvehicle bodies of automobiles and the like (JP 9-156088 A). However, amethod of adjacently printing a plurality of images on a surface of anobject having a three-dimensional shape, such as a vehicle body of anautomobile or an aircraft, with inkjet nozzles supported on an X-Y tableconstituted by an X-axis moving mechanism and a Y-axis moving mechanismand moving on a coating-target surface in XY directions, has not beenprovided yet. In such a case, drawing has been directly performed byhands or printed films have been pasted together and applied.

SUMMARY

That is, in the case of adjacently printing a plurality of images on asurface of an object having a three-dimensional shape with inkjetnozzles mounted on an X-Y table, and for example, in a case of printinga two-dimensional rectangle on a surface (spherical surface) of aspherical object with the inkjet nozzles, as illustrated in FIG. 7A, anink emitted through each of the inkjet nozzles mounted on a nozzle head100 is discharged in a direction perpendicular to the nozzle head 100,and therefore, a rectangle having a shape of distorted peripheral sides,as illustrated in FIG. 7B, is printed on a surface of a coating-targetobject 101. Then, in a case where another rectangle image is furtheradjacently printed to a printed print image 102 a in the X direction, anon-print area 103 that is an uncoated portion is generated between theprint image 102 a and a print image 102 b, as illustrated in FIG. 7C.That is, there is a problem that adjacent end edge portions of the printimage 102 a and the print image 102 b cannot be continuously printed. Aboundary portion of the two print images may overlap in some casesdepending on the shape of the surface of the object having athree-dimensional shape. Therefore, conventionally, there are no methodsof adjacently and continuously printing a plurality of images on athree-dimensional coating-target object by an inkjet method, and in thecase of printing an image on a three-dimensional body, drawing needs tobe directly performed by hands or printed films need to be pastedtogether and applied.

Therefore, the present invention has been made in view of the problemand an object is to provide a three-dimensional printing method capableof continuously performing printing without leaving an uncoated portionor causing an overlapping portion in adjacent side portions of eachprinted images even in a case of adjacently printing a plurality ofimages on a surface of an object having a three-dimensional shape withinkjet nozzles mounted on an X-Y table.

To solve the above-described problem, the invention according to claim 1is a three-dimensional printing method for printing an image havingcontinuity as a whole by adjacently printing a plurality of images on aprint-target surface including a non-plane portion by an inkjet nozzleattached to an XY table, the method including capturing a plurality ofsubdivided images by capturing a predetermined area of the print-targetsurface at fixed intervals to include an end edge portion of apreviously printed image on the print-target surface, the end edgeportion serving as a connection portion with an image to be printedcontiguous to the printed image while causing a capture unit attached tothe XY table to scan the print-target surface in XY directions in astate where the capture unit is disposed opposite to the print-targetsurface, creating a composite print surface which is a plane projectionof the print-target surface which is non-plane, by compositing theplurality of subdivided images captured by the capture unit,superimposing the image to be printed contiguous to the printed image(hereinafter, the image is referred to as “image to be drawn”) on thecomposite print surface, and editing the image to be drawn to becontinuous with the end edge portion of the printed image, anddischarging an ink on the print-target surface to perform printing by aprint head attached to the XY table on the basis of an edited image tobe drawn which is obtained by editing the image to be drawn.

According to the three-dimensional printing method of the presentinvention, the composite print surface, which is a plane projection ofsubdivided images of a print surface having a three-dimensional shapecaptured by the capture unit attached to the XY table, is created, andprinting is performed by an inkjet printer on the basis of the editedimage to be drawn, which is obtained by editing the image to be drawn tobe superimposed on the composite print surface. Therefore, there is aneffect to continuously print a plurality of images on a surface of anobject having a three-dimensional shape without gap or overlap.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a configuration diagram illustrating an embodiment of aninkjet printer implementing a three-dimensional printing methodaccording to the present invention;

FIG. 2 is an explanatory diagram illustrating an arrangement example ofthe inkjet printer illustrated in FIG. 1 for an automobile that is anobject be printed;

FIG. 3 is an explanatory diagram illustrating another arrangementexample of the inkjet printer illustrated in FIG. 1 for the automobileto be printed;

FIG. 4A is an explanatory diagram illustrating capturing of subdividedimages by a camera, and FIG. 4B is a diagram illustrating a compositeprint surface;

FIG. 5A is a diagram illustrating an image to be drawn, and FIG. 5B is adiagram illustrating an edited image to be drawn;

FIG. 6A is a diagram for describing an area where first printing hasbeen completed, and FIG. 6B is an explanatory diagram of an image to beprinted next; and

FIG. 7A is an explanatory diagram of a case where an image is printed ona spherical surface by an inkjet printer, FIG. 7B is an explanatorydiagram illustrating a result of a case where a rectangle is printed ona spherical surface, and FIG. 7C is an explanatory diagram of a casewhere rectangles are continuously printed on a spherical surface by aninkjet printer.

DETAILED DESCRIPTION

[Overall Configuration of Inkjet Printer]

A three-dimensional printing method according to the present inventionwill be described below in detail on the basis of a favorableembodiment. First, a configuration of an inkjet printer that implementsthe three-dimensional printing method according to the present inventionwill be described. FIG. 1 is a configuration diagram illustrating aconfiguration of an inkjet printer to which a three-dimensional printingmethod according to the present invention is applied. An inkjet printer1 illustrated in FIG. 1 roughly includes a print head 2 by an inkjetmethod, a camera 4 as a capture unit disposed in the vicinity of theprint head 2, an X-Y table 3 that moves the print head 2 and the camera4 in an X direction and a Y direction, a control unit 9 that operatesthe X-Y table 3 and discharges an ink from the print head 2 to controlprinting on a print-target surface on the basis of image editingsoftware S for editing an image captured by the camera 4 and a presetcontrol program, and a drive unit 11 that causes the camera 4 and theprint head 2 to be located at predetermined positions on the basis ofcontrol from the control unit 9, and performs capture and printoperation.

[Configuration of Each Part]

The print head 2 includes a plurality of nozzles (not illustrated) thatdischarges an ink toward a coating-target surface of a coating-targetobject M. Note that the “ink” referred hereto includes “paint”. Inks aredischarged through the nozzles perpendicularly to the print head 2. Thatis, an ink discharge surface of the print head 2 is parallel to an X-Yplane formed by the movement of the X-Y table 3, and ink dots dischargedthrough the nozzles are discharged in a direction perpendicular to theX-Y plane. In addition, discharging directions of the inks dischargedthrough the nozzles are parallel to one another. The nozzles arerespectively connected with ink tanks of predetermined colors, and theink tanks are pressurized by a pressurizing device (not illustrated).The nozzles can discharge the ink dots to a print surface of thecoating-target object M without problems as long as the distance betweenthe nozzles and the print surface is about 20 cm.

The X-Y table 3 roughly includes an X shaft 5 formed with a linearmovement mechanism, and a Y shaft 6 that moves the X shaft in the Ydirection while holding the X shaft 5 with two arms, and the print head2 and the camera 4 described below are attached to a slider (notillustrated) of the X shaft. A shaft 7 is provided on the Y shaft 6 andis held by a robot arm 8, whereby the print head 2 can be freelyarranged at a predetermined position where printing is to be performedon the coating-target object M. For example, in a case where thecoating-target object M is an automobile, the print head 2 can bearranged at a side position as illustrated in FIG. 2 or arranged on anupper portion as illustrated in FIG. 3. Note that the operation of therobot arm 8 is controlled on the basis of a program stored in advance inthe control unit 9.

The camera 4 is disposed on a slider (not illustrated) of the X shaft 5,which is a vicinity of the print head 2, and captures a predeterminedarea of the print-target surface of the coating-target object M at fixedintervals while moving in X-Y directions. The camera 4 is a so-calleddigital camera, and a specification of a lens that can capture aplurality of subdivided images for the predetermined area of theprint-target surface, as described above, and specifications of aresolution and the like are appropriately selected. The capturing of theplurality of subdivided images of the print-target surface by the camera4 is continuously and automatically performed according to a programprovided in advance in the control unit 9.

The control unit 9 is configured by a so-called microcomputer includinga storage device that records and stores various programs, data ofcaptured images, data of images to be printed, and the like, a centralprocessing unit that executes various types of processing according to aprogram, an input device such as a keyboard and a mouse, and a DVDplayer and the like as needed. Further, a monitor 10 is included, andthe monitor 10 displays input information to the control unit 9, aprocessing result by the control unit 9, and the like. As will bedescribed below, the control unit 9 performs image processing for aplurality of subdivided image data captured by the camera 4 using imageprocessing software, generates a composite print surface that is a planeprojection of the print-target surface which is non-plane of thecoating-target object M, and generates an edited image to be drawn B bysuperimposing, on the composite print surface, an image to be drawn Athat is an image to be printed contiguous to an printed image previouslyprinted on the print-target surface, and editing the image to be drawn Ato be continuous with an end edge portion of the printed image. Forexample, the control unit 9 generates, regarding a print image 102 b(corresponding to the image to be drawn A) illustrated in FIG. 7C, theedited image to be drawn B by editing (deforming) the print image 102 bto be consistent with the composite print surface so as not to form anon-print area 103 between the print image 102 b and an adjacent printimage 102 a. Then, by actually performing printing by the print head 2on the basis of the edited image to be drawn B, the print image 102 bcan be printed without a gap between the print image 102 b and theprinted print image 102 a. Note that implementation of the capturing ofthe plurality of subdivided images by the camera 4 and the printing bydischarge of the inks through the nozzles of the print head 2 isperformed by the drive unit 11, the operation of which is controlled bythe control unit 9.

[Operation of Inkjet Printer and Coating Method by Inkjet Printer]

Next, a three-dimensional printing method according to the presentinvention will be described together with the operation of the inkjetprinter 1 configured as described above. Here, it is assumed that thecoating-target object M is a vehicle body of an automobile, an image isprinted on a side surface of the automobile that is the coating-targetobject M, and a next image is printed contiguous to a previously printedimage I.

[Step 1] Regarding an image to be printed first, there are no specificrestrictions concerning a print position, and the image may just beappropriately printed at a position predetermined to a certain extent.To be specific, when the start of printing is instructed via the controlunit 9, the drive unit 11 operates the robot arm 8 to cause the X-Ytable 3 to locate the print head 2 on the side surface of thecoating-target object M, and performs the first printing. For example,the print image I illustrated in FIG. 6A is printed. This printed imageI serves as a reference image when the next print image, that is, theedited image to be drawn B (see FIG. 6B) is printed.

[Step 2] When the above-described first printing is completed, the nextimage is printed to be adjacent to and continuous with the printed imageI. To be specific, the robot arm 8 is operated via the control unit 9 tolocate the X-Y table 3 to face the print-target surface so as to includea position adjacent to the printed image I, that is, an area to beprinted next. At this time, the camera 4 is located to include an areaincluding a side contiguous to the printed image I, i.e., a right endportion 13 of the printed image I in the present embodiment, and thearea slightly broader than a area in which the image to be drawn A (seeFIG. 5A) as the next image should be printed. Then, this area iscaptured by the camera 4 as subdivided images that are obtained bydividing the area into small areas, for example, divided areas d, eachhaving a size of 20 mm×20 mm (see FIG. 4A). In a case where the area tobe printed is m×n, subdivided images divided into about 2,000 to 3,000images are captured. Then, image data D of the subdivided images isacquired. Note that the captured subdivided images can be displayed onthe monitor 10 by the control unit 9.

[Step 3]

Next, the control unit 9 composites the m×n subdivided images capturedby the camera 4 to one image. That is, the subdivided images areobtained by capturing the print-target surface of the coating-targetobject M which is non-plane, and a composite print surface C, which is aplane projection of these subdivided images, is created. Note that thesize of the subdivided image is not limited to 20 mm×20 mm, and if thesubdivided image is made smaller than the aforementioned size, acomposite print surface C with higher precision can be created. Further,in a case where the print-target surface of the coating-target object Mdoes not have much unevenness, a subdivided image having a larger sizethan the aforementioned size may be used.

[Step 4]

Next, the image to be drawn A as the image to be printed next issuperimposed on the composite print surface C contiguous to the printedimage I, and the image to be drawn A is edited contiguous to the endedge portion of the printed image I. For example, assuming that theprint image 102 b illustrated in FIG. 7C is the image to be drawn A,image editing is performed to expand a left-side end edge portion of theprint image 102 b to cover a portion corresponding to the non-print area103, and the edited image to be drawn B is generated. That is, an imageobtained by editing the print image 102 b to be continuous with theprinted image 102 a is the edited image to be drawn B. The generation(editing) of the edited image to be drawn B is executed by the controlunit 9 by the image editing software S while watching the monitor 10.

More specifically, the control unit 9 generates one composite printsurface C (see FIG. 5B) which is plane projection by compositing theplurality of “m×n” subdivided images captured by the camera 4. Next, thecontrol unit 9 superimposes the image to be drawn A (see FIG. 5A) as theimage to be printed contiguous to the printed image I on the compositeprint surface C, as illustrated in FIG. 5B, and further edits the imageto be drawn A to form a correction portion 12 that is expanded to causea left end portion of the image to be drawn A to be in contact with aboundary of the right end portion 13 of the printed image I, thereby togenerate the edited image to be drawn B. Note that “Adobe Photoshop”(registered trademark) of Adobe Systems Incorporated can be used as theimage processing software S for generating the edited image to be drawnB from the image to be drawn A, for example.

[Step 5]

Next, the inks are discharged through the nozzles of the inkjet printeronto the print-target surface of the coating-target object M to performprinting on the basis of the created edited image to be drawn B. Notethat the X-Y table 3 is held at the same position from the start ofcapturing of the subdivided images by the camera 4 to termination of theprinting of the edited image to be drawn B.

[Step 6]

When the printing of the edited image to be drawn B is completed, theprocessing of steps 1 to 5 described above is further repeated withreference to a printed image W (see FIG. 6B), whereby a plurality ofimages can be continuously printed on the coating-target object M.Further, in a case of continuously printing images above, below, or onthe right side of the first printed image I, the processing of steps 1to 5 described above is similarly repeated, whereby a plurality ofimages can be continuously printed on the coating-target object M.

Effect of Embodiment

As described above, according to the three-dimensional printing methodof the present invention, images having continuity without gap oroverlap can be printed even in the case of continuously printing aplurality of images on the surface of the three-dimensionalcoating-target object M. As a result, printing by an inkjet printer canbe performed on a vehicle body of an automobile or a body of an aircrafthaving a three-dimensional surface shape.

OTHER EMBODIMENTS

Note that the present invention is not limited to the above-describedembodiment, and various modifications can be made without departing fromor altering the technical idea of the present invention. For example, inthe above-described embodiment, the coating-target object as the objectto be printed has been the vehicle body of an automobile. However, itgoes without saying that the present embodiment is applicable to anaircraft, a ship, a railway vehicle, an industrial equipment, or thelike having a three-dimensional print surface.

Further, the three-dimensional printing method according to the presentinvention does not cause an uncoated portion or an overlapping portioneven in the case of dividing the surface of the coating-target objecthaving a three-dimensional surface shape into the plurality of areas andperforming printing, and therefore uniform coating can be performed.Therefore, the three-dimensional printing method according to thepresent invention is widely adoptable not only to printing of designimages and the like but also to coating with a single color. The type ofthe ink discharged through the print head 2 can be appropriatelyselected from aqueous inks and oil inks depending on the material thatcomposes the coating-target object, and the like.

What is claimed is:
 1. A three-dimensional printing method for printingan image having continuity as a whole by adjacently printing a pluralityof images on a print-target surface including a non-plane portion by aninkjet nozzle attached to an XY table, the method comprising: capturinga plurality of subdivided images by capturing a predetermined area ofthe print-target surface at fixed intervals to include an end edgeportion of a previously printed image on the print-target surface, theend edge portion serving as a connection portion with an image to beprinted contiguous to the printed image while causing a capture unitattached to the XY table to scan the print-target surface in XYdirections in a state where the capture unit is disposed opposite to theprint-target surface; creating a composite print surface which is aplane projection of the print-target surface which is non-plane, bycompositing the plurality of subdivided images captured by the captureunit; superimposing the image to be printed contiguous to the printedimage (hereinafter, the image is referred to as “image to be drawn”) onthe composite print surface, and editing the image to be drawn to becontinuous with the end edge portion of the printed image; anddischarging an ink on the print-target surface to perform printing by aprint head attached to the XY table on the basis of an edited image tobe drawn which is obtained by editing the image to be drawn.